let obj = {
  site: "后盾人",
  show() {
    console.log(this.site); //后盾人
    console.log(`this in show method: ${this}`); //this in show method: [object Object]
    function hd() {
      console.log(typeof this.site); //undefined
      console.log(`this in hd function: ${this}`); //this in hd function: [object Window]
    }
    hd();
  }
};
obj.show();